190 
Fig. 1. 
MR. O. THOMAS ON THE 
Priate XVII, 
Skull of Steatornis caripensis, adult, side view. 
2. Skull, upper view. 
PR oo 
Fig. 
G0 FT OU G0 bo 
Fig. 1. 
» lower view. 
. Lower jaw, upper view. 
Puate XVIII, 
Skull, end view. 
Os hyoides, upper view. 
Atlas, front view. 
. Axis, front view. 
Last dorsal vertebra, front view. 
hind view. 
” ” ” 
. Shoulder-girdle and sternum, lower view. 
3 ve 5 side view. 
Puate XIX. 
Cervical and dorsal vertebrx and ribs, side view. 
la. Last four cervical ribs. 
Ou o9 bo 
Fig. 
Oop oo toe 
” ” 
. Left leg, side view. 
. Part of same, front view. 
. Pelvis and caudal vertebra, side view. 
3 upper view. 
Prater XX. 
. Left wing, outer view. 
Part of same, inner view. 
. Tarso-metatarsus, top view. 
. Tibia, lower part, front view. 
. Ankle-joint, side view. 
Pelvis, lower view. 
13 diam. 
2 diam, 
— 39 . 
Nat, size. 
” 
Nat. size. 
Nat. size. 
2 diam. 
” 
” 
Nat. size. 
2. Preliminary Notes on the Characters and Synonymy of 
the different Species of Otter. 
Natural History Museum. 
[Received March 13, 1889.] 
By Ouprietp THomas, 
One of the most interesting and at the same time most difficult 
groups of Mammals is that of the Otters, a group which many 
zoologists have tried to work out wholly or in part, but which, owing 
to the striking resemblance of the species to one another, to the 
difficulties of obtaining large series, and to the variability of the 
different forms, has remained to this day in a terrible state of con- 
fusion, both as to systematic arrangement and nomenclature. 
The present paper does not pretend to be anything like a complete 
monograph of the group, but only attempts to clear up such points 
in the history of the species as are at present capable of elucidation, 
while leaving for future investigation many questions which cannot 
be settled for want of still further material. 
In connexion with this paper I have to thank sincerely Dr. F. A. 
Jentink, of Leyden, Prof. Pouchet and Mons, J. Huet, of Paris, 
